Electrical apparatus



July 2, 1929. F. F. STARR 1,719,089

' ELECTRICAL APPARATUS Original Filed Feb. 24, 1923 lPatented July 2,I 1929.

UNITED STATES PATENT OFFICE.

FRANK F. STARR, OF DAYTON, OHIO, ASSIGNOR TO DELCO-LIGHT COMPANY, OF

- DAYTON, OHIO, A CORPORATION 0F DELAWARE.

ELECTRICAL APPARATUS.

Application filed February 24, 1923, Serial No. 621,026. Renewed July 14, 1925.

kind referred to which is not affected by en-v l vironment temperature.

with the contacts open;

Fig. 3 is a plan v iew, partly in section, of the switch; and r Fig. 4 is a fragmentary sectional view taken on the line 4 4 of F ig. 3.

The disclosed form of the invention includes a pair of contacts in the circuit to be controlled and a lever for carrying one of these contacts. The lever is held in contact making position by means of a latch attached to a bimetallic temperature responsive device which is made compensating for changes in environment temperature. A heating coil in the controlling circuit heats the thermostatic latch causing the movable contact to be separated from the stationary one by means of a spring.

Referring to the drawings, a base 2O of non-conducting material supports terminals 21 and 22 adapted to be connected with a circuit to be controlled by the circuit breaker. Terminal 21 is provided with a block 23 upon which is pivotally mounted a lever 24 carrying a resilient arm 25 having a contact 26 riveted' thereto. As shown in Fig. 1, contact 26 is adapted to engage a contact 27 attached to the terminal 22. l A spring member 28 attached to block. 23 by screw 29 has its free end interposed in the path of movement of levier 24 to eifectfseparation of contacts 26 and 27 when the lever 24 is released from` the latching means.' Lever 24 is provided vvith a. handle 30 and with a latch plate 31 secured' to lever 24 by means'of screw 32 passing through a slotl 33 in plate 31. Obviously the plate 31 may be adjusted along the lever 24.

The plate 31 is adapted to be engaged by a latch 34 secured at the free end 'of a bimetallic thermostat blade 35 mounted upon a heat insulating post 36 extending from the base 20. A heat insulating link 37 connected with straps37a and 37'b connects the bimetallic blade '35'with a similarbimetallic blade 38 of the same length as blade 35 and arranged substantially parallel thereto., The blade 35 is arranged to bow upwardly or away from the: base 20 when heated,

whereas the blade 38 will bow downwardly with increase of temperature. As long as blades 35 and 38 are maintained at thefsame temperature, the latch 34 will tend to remain in theiposition shown in Fig. 1, although there may be changes in temperature in the blades 35 and 38.

In order to cause the lat-ch 34 to release the leverv24 after a certain duration of current flow in a controlling circuit, the switch base 20 is provided with terminals 40 and 41, which are adapted to be connected in the controlling circuit. One end of a heating coil 42, surrounding the blade 35 but; insulated therefrom, is attached tol the terminal 40 and the other.` end thereof is at tached to the terminal 41. yThe heating coil 42 is enclosed with-in a heat insulating' and electrically insulating sleeve 43. The insulating lin-k 37 and insulating post 36 pre- A vent the ready conduction of heat from `the blade 35 to the blade 38 whenthe blade'35 is being heated by the heating coil 42.

Normally the contacts 26 and 27 yare closed as shownin Fig. 1. When current flows through the heating coil 42 for a cery ample, reference is made to the copending' application of Starr and Harlan, Serial No. 629,108, tiled March 31, 1923. This application discloses a. battery charging system in which an internal-coinbustion engine drives av dynamo to cause. it to charge a storage battery. Electrical ignition is provided for the engine and the dynamo is caused to operate on battery current as al motor to crank the engine. The crankingr circuit is brought. into operation automatically and in the automatic system there is used what is known as a. cranking cut-out for interrupting the ignition circuit to the engine in case the. engine fails to start within a certain period oftime. In order to use the present invention iii such an automatic system, the terminals 'and 4llare connected in the cranking circuit from the battery to the dynamo, and the terminals 21 a-nd 2Q are connected to the ignition circuit. Obviously if the engine does not start as soon :is it should, the temperature responsive latch will function to release the lever 24, and thereupon the ignition circuit will be broken by separation of contacts 26 and QT. In the automatic system referred to, the heating coil for the thermostatic latch is cut out in case the engine becomes self-operative within a predetermined time.

The present invention can be advantageously used in such an automatic system since it is not substantially aected by environinent temperature. The adjustment ot the latch plate can be used advantageously. In case more time should be allowed tor the normal engine starting period the latch plate 3l can be shifted away from the tulcrum of lever 24, thereby increasing the initial bending stress iii the blade Consequently the blade 35 must be heated to a higher temperature before it will release the latch 3l. The current flowing. through thev heating coil 42 being the same for all conditions, the cranking circuit will remain established for a longer period before the ignition contactsv will be separated.

lVhle the form of mechanism herein Vshown and described constitutes a preferred embodiment ofone form of invention it is to be understood that other forms might be adopted and various changes and alterations made in the shape, size, and proportion of the elements therein without departing from the spirit and scope of the invention.

lVhat is claimed is as follows: y

1. An automatic circ-uit breaker comprising in combination, a support-ing base; 4two similar bimetallic thermostat blades; means for securing the blades at one end of each to the base in such manner that the blades will be located substantially parallel with like metal strips facing; a thermally non-conducting link pivotally connected with the blades adjacent the free ends thereof; a switch supported by the base and having a movable contact; a spring tending to separate the movable Contact from a stationary switch contact; means for maintaining the switch contacts in engagement and including a latch plate connected with the movable contact and a latch for engaging the plate and carried by one of the blades; and electrical means for heating one only of the blades.

u 2. An automatic circuit breaker comprising, in combination, a supporting base; two similar bimetallic thermostat blades located in parallelism with like metal strips facing; means for securing the blades at one end of each to the base in spaced relation, substantially parallel to the base and in such manner that the blades may move at right angles to the base; a thermally non-conducting link pivotally connected with the blades adjacent the free ends thereof; a switch supported bv the base and having a movable contact pix:- otally mounted to swing in a plane parallel to the plane of movement of the blades; a spring tending to separate the movable contact from a stationary switch contact.; a latch carried by one of the blades; a latch plate connected with the movable contact and retained in switch closine position by the latch when the plate is su stantially at right angles to the base; and electrical means for heating one only of the blades.

3. An automatic circuit breaker comprising in combination, two similar thermostatic elements having one end of each fixed. the free ends of the elements being arranged to tend to move opposite to one another with changes in environment temperature: a thermal non-conducting link for pivotally connecting the free ends of said elements and for maintaining said elements substantially parallel at all times; means for varying the temperature of one of the elements relative to the other for moving said elements; and

mechanism controlled by the movement of said elements.

4. An automatic circuit breaker compris- .ingr in combination, two similar elements havdition diti'erent. to that of the other for-mov ing said elements; and mechanism controlled by the movement of said elements.

In testimony whereof I hereto ax my signature. l

FRANK F. STARR. 

